Various devices have been developed for the automatic manufacture of concrete masonry blocks. For example, Bernham et al, U.S. Pat. No. 4,214,655, disclose a machine for the automated casting, curing, moving and stacking of concrete blocks. Jenkins, U.S. Pat. No. 4,132,492, discloses a self-propelled concrete screed machine having a winch and cable propulsion system.
Whissell, U.S. Pat. No. 4,802,836, discloses a compaction device for concrete block molding. Pardo, U.S. Pat. No. 4,909,717 and counterpart UK Patent Application No. 2,213,095A, discloses a concrete masonry casting apparatus incorporating reciprocal actuating plungers which cause a shape modification of blocks during casting.
However, automated block molding processes often cannot provide blocks of varying size with a high level of detail or ornamentation having the required structural integrity. For example, wet concrete fill used in the manufacture of blocks often transfers moisture to the stripper shoe during the process of compaction. Once wet, the stripper shoe becomes sticky due to the moisture present at its surface. As a consequence, fill material may stick to the stripper shoe.
The shoe may become fouled with mix, especially in indented areas used to form ornamentation, design, or detail on the blocks. In turn, various intended features of the block may be malformed or completely omitted as indentations or patterning on the stripper shoe are clogged or fouled with concrete mix. Ultimately this results in block features which are malformed and further eroded during curing and use. This problem fails to lend itself to the efficient manufacture of blocks having the required structural integrity and the intended level of detail or ornamentation.
However, in overcoming the problem of stripper shoe fouling, several requirements of automated manufacture must be satisfied. The elements of the block molding machine must withstand automated block molding processes which often involve a high degree of vibration, dirt, and compression, among other environmental stresses. Electrical elements are often not capable of surviving over a long term period under these conditions. Further, head assemblies must be serviceable to provide for operator safety as well as easy disassembly.
As a result, a need exists for a non-fouling stripper shoe and stripper shoe/mold assembly allowing for the formation of concrete masonry blocks of a high level of detail which at the same time provides for easy serviceability, operator safety, and longevity in an environment of high manufacturing stress.